A comparison of corrosion, tribocorrosion and electrochemical impedance properties of pure Ti and Ti6Al4V alloy treated by micro-arc oxidation process

• Published in: Applied surface science Vol. 324; pp. 751 - 756
• Main Authors: Fazel, M., Salimijazi, H.R., Golozar, M.A., Garsivaz jazi, M.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-01-2015
• Subjects: Corrosion; Corrosion resistance; Electrochemical impedance spectroscopy; Micro-arc oxidation; Morphology; Oxidation; Oxides; Pure Ti; Ti6Al4V; Titanium; Titanium base alloys; Tribocorrosion; Wear; Tribocorrosion; Pure Ti; Corrosion; Micro-arc oxidation; Ti6Al4V; Electrochemical impedance spectroscopy
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.11.030

•Unlike the volcanic morphology of MAO/Ti, MAO/Ti6Al4V showed many vermiform slots.•EIS analysis showed a lower capacitance of barrier layer for MAO/Ti specimens.•In MAO/Ti sample fretting fatigue cracks propagate and caused coating delamination.•Abrasive wear was the dominant mechanism in tribocorrosion of MAO/Ti6Al4V sample.
In this paper, the micro-arc oxidation (MAO) coatings were performed on pure Ti and Ti6Al4V samples at 180V. The results indicated that unlike the volcanic morphology of oxide layer on pure Ti, a cortex-like morphology with irregular vermiform slots was seen on MAO/Ti6Al4V sample. According to polarization curves, the corrosion resistance of untreated samples was significantly increased by MAO process. The electrochemical impedance spectroscopy analysis showed a lower capacitance of barrier layer (led to higher resistance) for MAO/Ti specimens. This indicates that corrosive ions diffusion throughout the oxide film would be more difficult resulted in a higher corrosion resistance. Tribocorrosion results illustrated that the potential of untreated samples was dropped sharply to very low negative values. However, the lower wear volume loss was achieved for Ti6Al4V alloy. SEM images of worn surfaces demonstrated the local detachment of oxide layer within the wear track of MAO/Ti sample. Conversely, no delamination was detected in MAO/Ti6Al4V and a mild abrasive wear was the dominant mechanism.